Heretofore dynamic testing of electronic devices, such as integrated circuits, has often involved soldering the electronic device to a printed circuit board having electrical contacts and electrical conductors electrically connecting the device to a power source and signal monitoring equipment. For example, in the case of vibrational testing and calibration of accelerometers, the printed circuit board is mounted to a shaker apparatus which is used to vibrate the printed circuit board and subject the device mounted on the printed circuit board to vibrations while it is powered and monitored to analyze the dynamic response of the device. A disadvantage with this method is that it is extremely time consuming, and therefore expensive, to solder an electronic device to a printed circuit board for testing. As a consequence, it is generally not practical to test each device in this manner. Accordingly, such testing, if used, is generally limited to a representative sampling of electronic devices from a production lot thereof. Although such random testing may be acceptable for certain applications in which a certain failure or defect rate can be tolerated, in many applications it is highly desirable, or even of critical importance, that each device be tested and/or calibrated under dynamic conditions to ensure that defective devices are not used. In such circumstances, alternative dynamic testing methods are desired to reduce cost. Another disadvantage with soldering the electronic device directly to a printed circuit board for dynamic testing of the device is that it is difficult to remove the device from the printed circuit board without damaging the pins or electrical leads of the electronic device. As a result, the cost of such testing is further increased on account of the time needed to remove the device from the printed circuit board and on account of the rejection of devices in which the pins or electrical leads are badly damaged. One way of eliminating the need to remove the electronic device from the printed circuit board is to solder the device to the actual printed circuit board on which the device is to be used. This modified technique, however, especially unsuitable is for conducive to high-speed, standardized testing because of the time lost soldering to the printed circuit board any electronic devices which prove to be defective, and because special adapters may be needed for mounting the device on test equipment when the electronic device is to be used on a plurality of different circuit boards of various sizes and shapes. Additional expenses may be associated with removing a defective electronic device from a printed circuit board to which it is soldered if the printed circuit board is reused, or with disposing of printed circuit boards and defective electronic devices attached thereto when the time needed to remove the device is not justifiable. Also, additional transportation costs may be associated with this technique, especially when the mounting of other devices to the printed circuit board is to be completed at another location remote from the location at which testing of the electronic device is to be performed. All of the above problems and associated costs are compounded and increased when a plurality of electronic devices which must be tested are to be mounted to a single circuit board.
Another technique which has been used in an attempt to overcome the problems associated with soldering the electronic device which is to be tested directly onto a printed circuit board is to clamp the electronic device to a circuit board having the appropriate contacts. This technique has involved applying pressure to the body of the electronic device which is to be tested to urge the pins or electrical leads of the electronic device against the appropriate contacts on the circuit board. This technique overcomes some of the problems associated with soldering, to a printed circuit board, the electronic device which is to be subjected to dynamic vibration testing. However, clamping the body of the electronic device introduces unpredictable vibrational distortions to the test system such that the electronic device being tested is not subjected to the same forces as are being applied by the shaker apparatus. As a result, it is not possible to determine the true response of the electronic device to selected vibrational forces provided by the shaker apparatus when using this technique. For many applications the errors associated with vibrational distortion caused by clamping the body of the electronic device to a circuit board are unacceptable. One particular application in which the vibrational distortions caused by clamping the body of the device being tested to a circuit board introduces unacceptable errors involves dynamic vibrational testing of accelerometer devices. In such cases where the precise response of the device to selected vibrational forces is of critical importance, the method of clamping the device to a circuit board by urging the body of the device toward the circuit board is entirely unacceptable. Another disadvantage with this technique is that the clamping forces needed to hold the device being tested on the circuit board during high frequency, high acceleration vibrational testing often cause damage to the pins or electrical leads of the electronic device. A further disadvantage of this technique arises when the electronic device is being tested to determine its dynamic response to vibrational testing at high and/or low temperatures. In such cases, the clamp contacting the body of the device being tested draws heat away from the device during high temperature testing, and supplies heat to the device during low temperature testing, making it impossible, or at least very difficult, to determine the true response of the device to vibrational forces as a function of temperature.
Another technique which has been used for testing of electronic devices, such as integrated circuits, having a body with a plurality of electrical leads emanating therefrom, is to use an apparatus provided with test sockets. The electrical leads of the electronic device which is to be tested are inserted into the sockets of the apparatus. Although use of these types of apparatuses involves less time mounting and demounting the electronic devices being tested than soldering techniques, a substantial amount of time and care must be taken to avoid damage to the electrical leads during mounting and demounting of the electronic device. As a result, the use of test sockets is not amenable to high speed automation. Further, these types of apparatuses having sockets for the electrical leads frequently suffer from loss of electrical contact between the leads of the electronic device and the socket contacts during high frequency, high acceleration vibrational testing. In other words, the electrical contacts between the device under testing and the test socket are not reliable when the test sockets are subjected to high shock and/or vibrational loads. As a result, erroneous test results can occur, which could potentially lead to the use of defective electronic devices and/or the rejection of non-defective electronic devices if the loss of electrical contact is not detected. Even if the loss of electrical contact is detected, such loss of electrical contact will require further testing of the device. Another problem with testing apparatuses having socket connections is that the physical connection between the sockets and the electrical contacts is of the type which tends to introduce unpredictable vibrational distortions, which cause the electronic device to be subjected to vibrational forces which are different from those provided by the shaker apparatus, ultimately resulting in recording of response signals from the device which are not indicative of the true response for the vibrational forces provided by the shaker apparatus. Also, because of the care which must be taken during mounting and demounting of the electronic device which is to be tested to prevent damage to the electrical leads of the electronic device, testing techniques using such apparatuses having sockets adapted to receive the leads of the electronic device which is to be tested are not well suited for high-speed automated testing.
Although the undesirability of soldered connections and socket type connections between electronic devices being tested and test fixtures have been recognized, the concept of clamping or clasping the electrical leads of the electronic device which is being tested between opposing surfaces of plates of a test fixture has not been successfully employed (especially for dynamic shock and vibrational testing) because of difficulty in establishing good electrical contact between all of the electrical leads of the electronic device being tested and the test fixture.